Front end lateral suspension

ABSTRACT

A suspension assembly for a front end of a vehicle to provide lateral flex for absorption of lateral forces. The suspension assembly comprises a steering shaft including two ends: an end coupled to an upper triple clamp and another end coupled to a lower triple clamp. A spring unit couples one of the two ends of the steering shaft to the associated triple clamp and absorbs forces that are transferred from a road surface up through a front wheel and the pair of forks retained by the upper and lower triple clamps. A pivot mechanism couples the other triple clamp to the other one of the two ends of the steering shaft and creates a pivoting axis. The suspension assembly permits the front end to pivot about the pivoting axis and causes the spring unit to flex laterally in response to bumps in the road surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/672,040, filed Feb. 6, 2007, and claims the benefit of U.S.Provisional Application Ser. No. 60/765,805, filed Feb. 6, 2006, whichis hereby expressly incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to a front end suspension forvehicles, and more particularly, to a suspension for absorbing lateralforces on a motorcycle.

BACKGROUND OF THE INVENTION

The extreme performance characteristics of modern day grand prix/racingmotorcycles have led manufacturers to develop very stiff front endpackages, designed to bear huge loads primarily during heavy braking.During this condition, the rearward force on the front tire's contactpatch presses rearward on the lower portion of the forks at the axle andthe inertia of the motorcycle's mass presses forward on the upperportion of the forks at the triple clamps. The resulting flex in thelongitudinal direction (direction of travel of the motorcycle) isminimized by increasing the rigidity of the forks.

This increased stiffness of the front forks solves the problem oflongitudinal flexing during braking. However, the compromise demanded bya stiffer front end is the appearance of chatter, or vibrationsresulting from momentary reductions of traction, particularly duringturns. Severe leaning angles typically result from motorcyclesnegotiating these turns and produce conditions conducive to chatter.When the motorcycle is leaning, the tire's contact patch shifts from thecenter to side, but the forces from the road are in the verticaldirection. Upon hitting little bumps, the vertical force transfers ontothe motorcycle mostly laterally. The inability of stiff forks to flex inthe lateral direction causes the bumps and imperfections of the roadsurface to lift up the vehicle, without any elastic restorative forcesof the forks being able to maintain pressure of the tire against theroad surface.

This problem leads to the vehicle losing contact with the road surfacewhich can result in chatter. Being vibration that resonates from thefront tire up to the chassis until dampened, chatter is a nuisance toriders and decreases motorcycle performance. Therefore, it is desirableto maintain longitudinal stiffness in the front end for rigidity underheavy breaking and at the same time, reduce chatter for improvedhandling of the motorcycle.

SUMMARY OF THE INVENTION

The present invention provides an apparatus for reducing chatter onfront ends of vehicles. This invention isolates two distinct stiffnessesof the front end: the longitudinal stiffness and the lateral stiffness.The desired rigidity of the longitudinal stiffness under heavy breakingis maintained, while the lateral stiffness is reduced to provide betterdampening under severe leaning angles, and consequently improvehandling. The foregoing and other features of the invention will be morereadily understood upon consideration of the following detaileddescription of the invention taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be understood more fully from the detaileddescription given below and from the accompanying drawings ofembodiments of the invention which, however, should not be taken tolimit the invention to the specific embodiments described, but are forexplanation and understanding only.

FIG. 1 is a perspective view of a motorcycle which includes a suspensionassembly according to the present invention.

FIG. 2 is a perspective view of a front end of a motorcycle including asuspension assembly.

FIG. 3 is a front view of the front end of the motorcycle including asuspension assembly and leaning to the right side, such as when themotorcycle is negotiating a right corner.

FIG. 4 is a front view of the front end of the motorcycle of FIG. 3encountering a bump and leaning to the right side, such as when themotorcycle is negotiating a right corner.

FIG. 5 is a front view of the front end of the motorcycle of FIG. 3encountering a bump and leaning to the left side, such as when themotorcycle is negotiating a left corner.

FIG. 6 is a front view of the front end of the motorcycle of FIG. 3using a spring unit that is more rigid than the spring unit in thesuspension assembly of FIGS. 3-5. The motorcycle is encountering a bumpand leaning to the left side, such as when the motorcycle is negotiatinga left corner.

FIG. 7 is a perspective view of a suspension assembly, including apivoting axis A and a steering axis B.

FIG. 8 is an exploded view of one embodiment of the suspension assembly.

FIG. 9 is an exploded view of an alternate embodiment of the suspensionassembly.

FIG. 10 is a perspective view of a spring unit for use in one embodimentof the suspension assembly.

FIG. 11 is an exaggerated perspective view of the spring unit of FIG. 10undergoing flex.

FIGS. 12-15 show perspective views of spring units for use in alternateembodiments of the suspension assembly.

FIG. 16 is a perspective view of an alternate embodiment of thesuspension assembly wherein the pivoting mechanism is located in theupper triple clamp and the spring unit is located in the lower tripleclamp.

FIG. 17 is a perspective view of another alternative suspension assemblyincluding a spring unit mounted in the upper triple clamp.

FIG. 18 is a perspective exploded view of the upper triple clamp, springunit, and a portion of the steering shaft of the suspension assemblyshown in FIG. 17.

FIG. 19 is a sectional view, at an enlarged scale, of a portion of theassembly shown in FIG. 17, taken along line 19-19 in FIG. 17.

FIG. 20 is a sectional view of the spring unit shown in FIG. 18, takenalong line 20-20.

FIG. 21 is a perspective view taken from the lower side of the portionof the upper triple clamp shown in FIG. 19, together with the associatedspring unit.

FIG. 22 is a perspective view similar to a portion of FIG. 18, showingan alternative spring unit for use in the suspension assembly shown inFIGS. 17-19.

FIG. 23 is a sectional view, taken along line 23-23 in FIG. 22.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, a motorcycle according to one embodiment of thepresent invention is shown at 10. The motorcycle 10 includes a front end12, an engine assembly 13, and a frame 14 supporting a rear wheel 16 viaa rear suspension 18. The front end includes a suspension assembly 20coupling a front wheel 22 to the frame and aiding in the absorption oflateral forces in certain conditions, as further described below.

Turning to FIG. 2, the front end of the motorcycle is shown in moredetail with several components removed. The front end 12 typicallyincludes a steering tube which is part of, or coupled to, the frame ofthe motorcycle, to house a steering shaft 24. For illustrative purposes,the steering tube and parts of the frame have been removed to showadditional detail.

The suspension assembly 20 includes the steering shaft 24, an uppertriple clamp 26, a lower triple clamp 28, a spring unit 30 and a pivotmechanism 32. The upper triple clamp and the lower triple clamp areadapted to retain a pair of front forks 34, 36 coupled to the frontwheel 22 via a front axle 38. Although the front forks are shownthroughout this application as non-telescopic forks, the scope of theinvention includes front forks having telescopic tubes, built-inrigidity or flex, dampers within, and fork bottoms for coupling to thefront axle. One or more of these features may be included in the frontforks. Other features of conventional front forks may also be used withthe front forks.

The suspension assembly 20 may separate flexional stiffness in thelongitudinal direction (direction of travel of the motorcycle) fromflexional stiffness in the lateral direction (side-to-side orperpendicular to the longitudinal direction). Flexional stiffness in thelongitudinal direction may be referred to as “longitudinal stiffness,”whereas flexional stiffness in the lateral direction may be referred toas “lateral stiffness.” By decoupling the longitudinal stiffness and thelateral stiffness in the front end, chatter may be reduced and handlingcharacteristics may be improved. Detailed mechanics of the suspensionassembly is described further below.

For simplicity, when the front end 12 is mentioned below, particularlyin describing movement, the front end refers to the entire front end ofthe motorcycle 10 without the steering shaft 24 (which is stationarywith respect to the frame). For further illustration and as non-limitingexamples, FIGS. 3-6 are provided to exemplify the movement of the frontend fitted with the suspension assembly 20. These depictions areexemplary only and may be exaggerated to show more detail.

Front views of the front end including the suspension assembly are shownin FIGS. 3-6. The front end of the motorcycle includes a steering axis40, extending coaxially through the steering shaft 24, and two fork axes42, 44, extending coaxially through each front fork 34, 36. The steeringshaft is adapted to rotate about the steering axis 40 to steer the frontend 12. In general, the steering axis and the two fork axes aresubstantially parallel during travel of the motorcycle. Referring toFIG. 3, the front end is turning right and leaning to the right side,such as when the motorcycle is rounding a right corner.

While the motorcycle is negotiating a corner, the motorcycle istypically leaning into the turn. The more the motorcycle leans, thegreater (steeper) the lean angle. The lean angle at which the turn ismade may vary depending on the turn radius, motorcycle speed, tirecharacteristics, rider handling, and the balance of centrifugal andgravitational forces. For example, the faster the speed and the smallerthe turn radius, the greater the lean angle on the motorcycle. When thefront end is at a steep lean angle, dampers that are designed to absorbforces in the vertical direction are ineffective at absorbing forceswhich are effectively acting in the lateral direction. As a result, thefront wheel loses contact with the ground and the inertia of the vehicleis slow to react. The suspension assembly may help solve this problem bydecreasing the lateral stiffness (or allowing additional flexibility) ofthe front end for better absorption of lateral forces and improvedcornering ability.

FIG. 4 depicts the response of the front end 12 shortly after themotorcycle encounters a bump 8 in the road when rounding a corner. Whenreferring to the bump, the terminology may include any imperfections inthe road or debris that may contribute an additional force to the frontend. This force is generally directed in the vertical direction, andimpacts the front end. This vertical force (effectively lateral force onthe leaning motorcycle) may be dampened using the suspension assembly.

The suspension assembly absorbs energy through deflection of a springunit, further discussed below, and separates these forces acting on thefront end from the frame to minimize the unsprung weight of themotorcycle. With less inertial weight, the front wheel of the motorcyclecan return to the road surface in less time.

In response to the bump in FIG. 4, the front end may shift laterally orroll slightly to the side with respect to the frame of the motorcycledue to the flexibility allowed by the suspension assembly. As shown inthis instance, the front forks move with respect to the steering shaft(which is stationary to the frame) and thus the steering axis and forkaxes are no longer substantially parallel.

As the front end hits the bump in the road while traveling at an initiallean angle, the spring unit allows for displacement of the front end.For example, in reaction to the bump, the steering shaft remainssubstantially inclined to the initial lean angle whereas the rest of thefront end has shifted to a different lean angle. During this instance,the front end may have a lean angle greater than the initial lean angle.FIGS. 3 and 4 may be contrasted to see the effect of the roadimperfection on the front end and the suspension assembly.

Referring to FIG. 5, similar to FIG. 4, the motorcycle encounters a bumpas it leans left into a left corner. The suspension assembly allows thefront end to shift laterally to a larger lean angle from an initial leanangle and to the opposite side from that depicted in FIG. 4. As shown,the steering shaft remains inclined at the initial lean angle while thefork axes are still parallel to each other, but have shifted to asteeper lean angle. The spring unit 30 absorbs lateral forces, similarlyas described above.

In contrast to FIG. 5, FIG. 6 shows the front end fitted with a stifferspring unit 31 in the suspension assembly. Depending on the rigidity ofthe spring unit, the lateral movement of the suspension assembly andfront end may be very small or not visible when the spring unit isabsorbing lateral forces.

Referring to FIG. 7, one embodiment of the suspension assembly 20 isshown. The upper triple clamp 26 is a shaped plate including retentionbraces 46 on each side for retaining and securing the front forks 34, 36(not shown). These retention braces may be adjusted to retain frontforks with varying diameters. In the middle is an aperture 48 forhousing the spring unit 30 and the steering shaft 24. The upper tripleclamp further includes screw holes 50 that align with the spring unitand allow screws (not shown) to fasten to the spring unit by insertingthrough the bottom or top of the upper triple clamp. Attaching thespring unit to the upper triple clamp is not limited to using screws andscrew holes, but may include using other fasteners and methods ofcoupling those components.

The steering shaft 24 is disposed substantially perpendicular to theupper triple clamp 26 and lower triple clamp 28. Optionally, thesteering shaft may couple to the upper triple clamp and the lower tripleclamp without the perpendicular relationship. The steering shaftincludes an upper end 52 that is adapted to couple to the upper tripleclamp and a lower end 54 that is adapted to couple to the lower tripleclamp. The steering shaft is held securely to the frame via bearings(not shown). Although the steering shaft is shown to be cylindrical, thesteering shaft may also be a rectangular prism or other suitablegeometry.

The lower triple clamp 28 may be similar in shape to the upper tripleclamp 26, and is oriented substantially parallel to the upper tripleclamp. The lower triple clamp may be thicker (greater in height) thanthe upper triple clamp for the inclusion of bearing pockets and bearings(not shown) (not to be confused with bearings coupling the steeringshaft to the frame). The bearing pockets are located on a front side anda back side of the lower triple clamp to house two bearings. Thebearings permit the pivot shaft to rotate and support the load that actson the suspension assembly.

The lower end 54 of the steering shaft 24 rests in the middle of thelower triple clamp 28 between the two retention braces 56. The lower endmay be adapted to allow pivotal movement in the lateral direction abouta pivot axis A, and/or the lower triple clamp provides a small clearanceso that the lower triple clamp can pivot about axis A. This range ofpivotal motion is limited by the flexibility or rigidity of the springunit 30 located at the other end of the steering shaft. It may be littleor no movement if the spring unit is very rigid or several degrees ifthe spring is less rigid or comprised of flexible material.

As mentioned above, when a typical motorcycle enters an orientationduring travel where there is little or no dampening, such as when it isleaning over at a great angle, the motorcycle may chatter and decreasefront wheel contact to the road surface. The suspension assembly maysolve this problem by providing lateral flex to the motorcycle withoutcompromising the rigidity necessary for hard braking. By decoupling thelongitudinal and lateral forces, the suspension assembly allows theabsorption of lateral forces and restores front wheel contact in lesstime.

Further, the front end may pivot about pivot axis A and at the sametime, rotate about a steering axis B for steering of the motorcycle. Inaddition, steering stops 58 may be coupled to the lower triple clamp 28to limit the range of motion in steering about axis B.

Turning to FIG. 8, one embodiment of the suspension assembly 20 is shownin exploded view. As described above, the suspension assembly includesupper triple clamp 26, a lower triple clamp 28, and steering shaft 24coupling the upper triple clamp to the lower triple clamp. The uppertriple clamp and the lower triple clamp are substantially parallel toeach other and the steering shaft is substantially perpendicular to thetriple clamps. Alternatively, the steering shaft need not besubstantially perpendicular to the triple clamps. The steering shaft iscoupled to bearings which secure it to the frame of the motorcycle.

The suspension assembly 20 further includes a spring unit 30 couplingthe upper triple clamp 26 and the steering shaft 24 together, and mayserve to absorb forces that may be transferred from the upper tripleclamp to the steering shaft and vice versa. The spring unit alsoinherently gives strength to the suspension assembly, in addition to thestrength provided by the bearings, as further discussed below.

The upper end 52 of the steering shaft may include a shoulder 60 toassist in supporting the spring unit and other components for ease ofcoupling. Other components that may be located in this area includebearings (not shown) and lock nuts for connecting the steering shaftsecurely to the steering tube and frame.

The suspension assembly 20 further includes a pivot mechanism 62. Asshown, the pivot mechanism may be a pivot shaft inserted through twobearings 64 located in bearing pockets 66 located in the lower tripleclamp and secured by a pivot nut 68. The pivot shaft rotates with thebearings, which may bear much of the load that acts on the suspensionassembly. The bearings help in maintaining longitudinal stiffness. Bolts70 attach a steering shaft cap 72 to the lower end of the steeringshaft, thus surrounding the pivot shaft and holding the pivot shaft sothat the steering shaft can pivot with the pivot shaft.

Alternatively, the steering shaft may pivot on a different kind of pivotmechanism. For example, a ball and socket joint pivot mechanism may beused where the steering shaft may include a socket that swivels on aball. The steering shaft or the lower triple clamp may include stops orgeometry to allow only one plane of motion of the steering shaft as itswivels.

FIG. 9 is an alternate embodiment of the suspension assembly 21 as shownin exploded view. This embodiment of the suspension assembly is similarto the embodiment pictured in FIG. 8, and may include different designsof different components of the suspension assembly. The designvariations do not change the general functionality of the suspensionassembly, but instead offer an alternate way of constructing thesuspension assembly. The design variations may include structuraldifferences of the upper triple clamp, lower triple clamp, spring unit,and steering shaft. Some of these design variations are readily visiblefrom the depiction of FIG. 9.

One of these design variations is the location of the bearing pocketsfor the coupling with the bearings and pivot mechanism. Instead ofhousing the bearings in the lower triple clamp, the bearings may behoused in the lower end 54 of the steering shaft at 74. The scope of theinvention includes other adaptations of the steering shaft to allow forconfigurations that are conducive to effectuate absorption of lateralforces acting on the front end.

Further, the suspension assembly of FIGS. 8 and 9 may include thecomponents illustrated in FIGS. 8 and 9 and although not mentioned, anywashers, spacers, o-rings, seals, screws, nuts and bolts, fasteners andother components that may aid in the function of the suspensionassembly. Optionally, dust seals may be included to prevent debris fromentering the suspension assembly.

Referring to FIGS. 10-11, an exemplary spring unit for use in oneembodiment of the suspension assembly is shown at 76. FIGS. 12-15 showexemplary spring units that may be used with alternate embodiments ofthe invention. Typically the spring units couple with the upper tripleclamp. Alternatively, the spring units may couple with the lower tripleclamp. As illustrated in a perspective view in FIG. 10, the spring unit76 may be constructed with an annular frame 78 including two ribs 80each connecting the annular frame with a center ring 82. The center ringincludes an attaching surface 84 to bolt the upper triple clamp 26 (notshown) to the steering shaft 24 (not shown). In this figure, theattaching surface is shaped as a square with rounded corners.

As shown, where the ribs connect to the annular frame and to the centerring, the junctions 86 are filleted. The radius of the fillets may bevaried to change the strength and rigidity of the spring unit.

It may be desirable to have extra strength in the longitudinal directionto withstand braking forces. By orienting the spring unit such that theribs are aligned longitudinally, this can be achieved. For alignment,the spring unit may include a mechanism which allows for aligning thespring unit to a particular orientation. The mechanism may be placementof multiple holes, a square-shaped bolt hole, or other indicator foralignment. Multiple holes 88 may be adapted for fasteners to insertthrough and couple the spring unit to the upper triple clamp.

FIG. 11 shows an exaggerated top view of the spring unit of FIG. 10undergoing flex as a spring. The ribs 80 and the center ring 82 may bedisplaced in the lateral direction (in this view, left and right) aswell as in the vertical direction (in this view, into the page and outof the page). The ribs and the center ring may be displaced in adirection opposite than what is pictured as well. While the spring unitis flexing to absorb energy, the lateral forces distribute between thetwo ribs. When the forces have been absorbed, the spring unit returns toa neutral position such as shown in FIG. 10. The deflection in thespring unit is exaggerated for illustrative purposes.

Referring to FIG. 12, a spring unit suitable for use with anotherembodiment of the suspension assembly is shown at 88. The spring unitmay be solid and constructed of a single material (shaded in thefigure), thus the ribs as described above may be used, but are notrequired. As an alternative, if increased lateral stiffness is desired,the spring unit may be a rigid, solid block that does not exhibitcharacteristics of a spring. This offers the option of switching back toa conventional suspension system without having to dismantle and rebuildthe front end in its entirety.

As illustrated in FIG. 12, the attachment means from the upper tripleclamp to the spring unit may be different. For example, multiple holesfor alignment or coupling to the upper triple clamp may be tapped forbolts to screw in from the top as shown as 90. In another example, thespring unit may include a raised concentric ring 92 with the outercircumference 94 threaded. In addition, the attaching surface asdescribed in FIG. 10 is circular shaped in this embodiment of the springunit. Further, the attaching surface may be tapered as shown at 96.

Referring now to FIG. 13, a spring unit 98 for use with an alternateembodiment may include an annular frame 100 with a center ring 102,similar to FIG. 12, with a vacant region 104 in between. Differentmaterials for dampening may fill in the vacant region for improvedabsorption. These materials may include rubber neoprene, air or nitrogenbladders, honey-combed structures and the like, anisotropic materials,and other dampening materials. By changing the material, the dampeningcharacteristics may be tuned to the desired amount and strengthened inthe desired direction (generally longitudinally)

The vacant region may further include ribs that may flex, for example,such as shown in FIG. 11. In an alternate embodiment, the vacant regionmay include more ribs, different rib widths, lengths and thicknesses,radial and other rib arrangements, and varying fillet radii, in additionto dampening materials mentioned above.

Turning to FIG. 14, in an alternate embodiment of the suspensionassembly, a torsion rod 106 may be used to strengthen a spring unit 108in the longitudinal direction. The spring unit may include an annularframe 110 with a center ring 112 and a passage 114 adapted for placementof the torsion rod. The passage is oriented parallel to the ribs 116,and cuts through the ribs and center ring. The torsion rod may includedetents 118 spaced apart that assist in holding the torsion rod in placeafter the torsion rod is inserted in the spring unit. The torsion rodmay be composed of titanium, steel, carbon fiber, aluminum or a morerigid material while the frame, ribs, and ring portions may be composedof aluminum or a different material.

It should be noted that the spring unit does not necessitate an annularframe with center ring formation. The spring unit may have a differentgeometry, and still function similarly to the spring units as described.The center rings as shown in the spring units above may not need to becentered, concentric, or ring-shaped. For example, FIG. 15 shows aspring unit without an annular frame that may be used with an alternateembodiment of the suspension assembly. The spring unit includes acylinder 122 with a hollow 124 in the shape of a cross. The spring unitfurther includes a spacer 126 shaped to fit inside the hollow andaccommodate coil springs 128. The coil springs are positioned in thesame orientation to enable the spacer to move in one general direction.The cylinder 122 and the spacer 126 may include shallow beds 130 whichseat the coil springs and keep them in place during operation. In thisconfiguration of the spring unit, the coil springs may be swapped withother springs to adjust to the desired flexibility of the spring unit.On certain inner surfaces of the spring unit where the spacer maycontact directly, a coating such as a fluoropolymer or friction-reducingmaterial may be applied.

The spring units as described may be alternatively constructed withdifferent shapes or characteristics to enable the suspension assembly tofunction as desired. It is within the scope of the invention for aspring unit to use a polygonal or elliptical frame instead of an annularframe. Further, the suspension assembly allows for adjustable lateralstiffness by swapping a spring unit with certain characteristics foranother one with different characteristics.

Additionally, these spring units may be partially or wholly manufacturedout of aluminum, steel, titanium, carbon fiber or other suitablematerials that may exhibit elastic properties and have sufficienttensile strength to withstand forces inflicted on the front end.Further, there may be other suitable materials, thicknesses, andvariations of the geometry well within the scope of the invention toprovide the desired longitudinal and lateral stiffness of the front end.

As shown in FIG. 16, an alternate embodiment of the suspension assembly132 may include locating a pivot mechanism 134 in an upper triple clamp136 while a spring unit 138 is located in the lower triple clamp 140.Both the pivot mechanism and the spring unit are coupled to a steeringshaft 142. The principle of operation is the same in that when themotorcycle is leaning, the forces may transfer similarly and allow thesuspension assembly to absorb lateral forces by pivoting about an axisC. Normal steering is unhindered as rotation of steering axis D isallowed.

As shown in FIGS. 17, 18, and 19, in another alternative suspensionassembly 150 an upper triple clamp 152 includes a shaped plate, such asa cast or machined metal member including a retention brace 154 on eachlateral side, for retaining and securing front forks 34, 36 (not shown).In the middle of the upper triple clamp 152 is an aperture 156 in whicha spring unit 158 is located. A movable end 159 of the spring unit 158defines a receptacle 162 into which a steering shaft 160 extends, as maybe seen better in FIGS. 18 and 19. A fastening bolt 164 extends throughthe receptacle 162 of the spring unit 158 into a threaded bore 166 inthe steering shaft 160 to securely fasten the upper end 168 of thesteering shaft 160 to the movable end 159 of the spring unit 158.

As with the previously described embodiments of the suspension systemdisclosed herein, the steering shaft 160 is disposed substantiallyperpendicular to the upper triple clamp 152 and to a lower triple clamp172. The lower triple clamp 172 may be similar in shape to the uppertriple clamp 152 and is oriented substantially parallel to the uppertriple clamp 152. The lower triple clamp 172 may also include bearingpockets and bearings (not shown) to receive a pivot shaft of a pivotmechanism (not shown) oriented generally longitudinally (of thesuspension assembly, and thus of the vehicle) so as to define a pivotaxis E.

The pivot shaft, similar to the pivot shaft shown in the pivot mechanism62 in FIG. 8, may be clamped to the lower end of the steering shaft 160by a clamp 174, so that the central axis F of the steering shaft 160intersects the pivot axis E of the pivot mechanism, as shown in FIG. 17.Since the attachment of the lower end of the steering shaft 160 to thepivot mechanism by the clamp 74 is generally similar to that shown inFIGS. 7 and 8, the manner of attachment is not shown in detail here. Byvirtue of the pivot mechanism the lower triple clamp 172 is able torotate about the axis E through a limited angle permitted by theclearance between the lower triple clamp 172 and the clamp 174 inresponse to lateral forces acting upon the forks of the frontsuspension.

Referring to FIG. 18, the movable end 159 of the spring unit 158 mayinclude an inwardly protruding annular ledge 178 to be clamped betweenthe head of the bolt 164 and the upper end 168 of the steering shaft 160in order to securely attach the upper end 168 to the movable end 159.

A mounting portion 180 of the spring unit 158 is located longitudinallyopposite the movable end 159 and includes a pair of oppositely laterallydirected arms 182 each defining a mounting bolt hole 184.

Extending longitudinally between the movable end 159 and the mountingportion 180 of the spring unit 158 are a pair of resiliently flexibleribs 186, 188. The ribs 186, 188 may have similar widths or thicknesses190 and depths 192, and the length 194 of each rib 186 and 188 extendslongitudinally with respect to the front suspension assembly 150. Itwill be understood that the compliance or flexibility of the spring unit158 will be variable by changing the thickness 190, depth 192, orseparation distance 196 between the ribs 186 and 188, or by varying thematerial of which the spring unit 158 is made.

As may be seen in FIGS. 19 and 20, the spring unit 158 fits in the underside of the upper triple clamp 152, with each of the arms 182 fittinginto a respective stall 198. Fitted mounting screws 200 extend intothreaded bores 202 to fasten the spring unit 158 securely into place inthe upper triple clamp 152. As shown best in FIG. 19, there is roomprovided in the upper triple clamp 152 to place a mounting screw 200 inline with the threaded bore 202, and an access opening 204 allows theuse of a suitable wrench to tighten the mounting screw 200 in place,extending through a fitted bore 205 in a web of the upper triple clamp152 and the respective bolt hole 184, into the threaded bore 202.

The aperture 156 in the upper triple clamp 152 is large enough toprovide a gap 206 around the movable portion 159 of the spring unit 158,so as to permit movement of the movable portion 159 laterally in eitherdirection as indicated by the arrow 208, as the ribs 186 and 188 areflexed by lateral forces acting on the front forks 34, 36 of the frontend and urging the upper and lower triple clamps 152 and 172 to moveabout the pivot axis E. The width 210 of the gap 206 may be used tocontrol the maximum flexure of the spring ribs 186 and 188 so as toallow a desired amount of lateral flexure of the suspension assembly 150so as to reduce chatter yet without sacrificing control, as the upperend 168 of the steering shaft 160 is permitted to move in the directionindicated by the arrow 208 through only the distance provided by thewidth 210 of the gap 206. It will be appreciated that during heavybraking of the front wheel of a motorcycle equipped with a suspensionassembly 150 the ribs 186 and 188 of the spring unit 158 will be intension and thus will tend to be centered by pendulum forces. It willalso be appreciated that, as in the suspension assembly 132 shown inFIG. 16, a spring unit 158 could be appropriately mounted in a lowertriple clamp and a pivot mechanism could be used to couple the steeringshaft 160 to an upper triple clamp.

A spring unit 212, shown in FIGS. 22 and 23, is generally similar to thespring unit 158, but its ribs 186′ and 188′ have a depth 192′ greaterthan the depth 192 of the ribs of the spring unit 158, so that thespring unit 212 is stiffer than the spring unit 158 if made of similarmaterial and if the other dimensions are similar. The spring unit 212thus might be more appropriate for a heavier motorcycle.

All of the disclosed components of the invention may each embodydifferent features as described that may provide advantages inmanufacture and assembly. Some of the features may be mixed and matchedon another embodiment of the invention and still be within the scope ofthe present invention.

While the invention has been described with reference to its use in amotorcycle, the invention is not limited to motorcycles, but can be usedin bicycles, dirt bikes, and other vehicles. Further, the invention maybe used with an “upside-down” suspension fork, or it may alternativelybe used with a traditional telescopic fork or a rigid fork.

Some components have been illustrated as being of monolithicconstruction, while other components have been illustrated as beingseparate components coupled together. It is within the scope of theinvention to combine these components or separate them due to design andmanufacturing considerations. For example, the steering shaft may beconstructed in multiple pieces for ease in manufacturing. The lower endof the steering shaft may be separately constructed as a block andcoupled to a threaded end of the steering shaft, and still allowingfunctionality like the steering shaft as pictured. As another example,it is feasible for the spring unit to be integrally constructed orpermanently attached to the upper triple clamp or the lower tripleclamp. This may offer the benefit of obviating the need for alignment oradditional assembly.

The skilled reader will further appreciate that the invention may bepracticed in a “single-sided” front end, such as that found on somebicycles which have only a single fork. The term “triple clamp” shouldnot necessarily be interpreted to mean that two forks are required withthe steering shaft. For example, one of the two forks may be coaxial tothe steering shaft or considered to be the steering shaft and the otherfork and the front end may pivot about the lower end of the steeringshaft. The presence of one or more springs or dampers coaxial to orcoupled to the steering shaft does not necessarily prohibit theadditional presence of one or more springs or dampers elsewhere, such aswithin the forks.

The various features illustrated in the figures may be combined in manyways, and should not be interpreted as though limited to the specificembodiments in which they were explained and shown. Those skilled in theart having the benefit of this disclosure will appreciate that manyother variations from the foregoing description and drawings may be madewithin the scope of the present invention.

The terms and expressions which have been employed in the foregoingspecification are used therein as terms of description and not oflimitation, and there is no intention in the use of such terms andexpressions of excluding equivalents of the features shown and describedor portions thereof, it being recognized that the scope of the inventionis defined and limited only by the claims which follow.

1. A suspension assembly for use with a front end of a vehicle, thesuspension assembly comprising: an upper triple clamp defining alongitudinal direction and a lateral direction; a lower triple clamp,the upper and lower triple clamps being adapted to retain a pair offorks and hold the pair of forks substantially parallel to each other; asteering shaft extending substantially perpendicularly between the upperand lower triple clamps; the steering shaft being adapted to be coupledto a frame of the vehicle and including two ends; a spring unit couplingan upper one of the two ends of the steering shaft to the upper tripleclamp, the spring unit being arranged to absorb lateral forces that aretransferred from a road surface up through a front wheel and the pair offorks; and a pivot mechanism coupling a lower one of the two ends of thesteering shaft to the lower triple clamp, the pivot mechanism defining apivot axis oriented longitudinally with respect to the suspensionassembly, wherein the front end pivots about the pivot axis and thespring unit flexes laterally of the triple clamps in response to bumpsin a road surface on which the vehicle is operated.
 2. The suspensionassembly of claim 1 wherein the spring unit includes a mounting portionattached to the upper triple clamp and a resiliently flexible memberextending in a longitudinal direction with respect to the vehicle fromthe upper one of the ends of the steering shaft to the mounting portion.3. The suspension assembly of claim 2 wherein said mounting portionextends laterally with respect to the resiliently flexible member of thespring unit.
 4. The suspension assembly of claim 2 wherein said mountingportion extends laterally and is mounted on the upper triple clamp. 5.The suspension assembly of claim 2 wherein said resiliently flexiblemember has a movable end coupled to the upper one of the ends of thesteering shaft.
 6. The suspension assembly of claim 5 wherein the uppertriple clamp defines a limited space on each lateral side of the movableend of the resiliently flexible member, and lateral movement of theupper end of the steering shaft in response to a lateral force acting onthe front end is limited by said limited space to a predeterminedmaximum distance.
 7. The suspension assembly of claim 2 wherein theresiliently flexible member is in tension during braking of the frontend of a vehicle equipped with the suspension assembly.
 8. Thesuspension assembly of claim 2 wherein the resiliently flexible memberincludes a pair of parallel ribs extending longitudinally and spacedapart laterally from each other.
 9. A suspension assembly for a frontend of a vehicle arranged to travel in a longitudinal direction, thesuspension assembly comprising: an upper triple clamp adapted to retainat least one front fork; a lower triple clamp adapted to retain said onefront fork and coupled to the upper triple clamp via a steering shaft,the lower triple clamp being substantially parallel to the upper tripleclamp; a spring unit coupling the steering shaft to a first one of thetriple clamps, the spring unit being adapted to absorb lateral forcesacting on the front end; and a pivot mechanism coupling the steeringshaft to a second one of the triple clamps, the pivot mechanismpermitting movement of the second one of the triple clamps about a pivotaxis not coaxial to the steering shaft, and wherein upon lateral forcesacting on the front end, the lower triple clamp continues to besubstantially parallel to the upper triple clamp, the front end shiftsabout the pivot axis of the pivot mechanism, and the spring unitundergoes flex to absorb lateral forces.